This invention relates, in general, to manufacturing techniques using glass substrates, and more particularly, to methods of marking glass.
Glass substrates are used as support substrates in fabricating cathodes for field emission devices. The glass substrates need to be identified by a unique mark so that the glass substrates can be distinguished from each other. Several marking techniques exist, but the techniques have many disadvantages.
For example, one technique for marking a glass substrate uses a diamond scribe to engrave a surface of the glass substrate. However, this engraving process forms grooves in the substrate and also creates many small glass particles, which produces contamination and cleaning problems. Additionally, this engraving process weakens the glass substrate, which may fracture. Furthermore, reliability concerns prohibit forming a glass frit seal over the engraved portions of the glass substrate. Therefore, the portion of the glass substrate used for identification purposes cannot also be used in field emission devices, which increases the cost of the devices.
As another example, a different technique for marking a glass substrate uses a metal-filled ink. In this technique, a writing utensil applies the ink to the surface of the glass substrate. However, this technique additionally requires a high temperature step to set and fuse the ink onto the surface of the glass substrate. Therefore, this technique also increases the cost and the cycle time of the manufacturing process for the field emission devices.
Accordingly, a need exists for a method of marking glass that is non-destructive, does not weaken the glass, does not degrade the reliability of the devices formed over the glass, does not significantly increase the cost of the devices formed over the glass, and does not significantly decrease the throughput of the manufacturing process for the device.